1 /*
2 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
3 * All Rights Reserved.
4 *
5 * Copyright © 2012 Intel Corporation
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the next
15 * paragraph) shall be included in all copies or substantial portions of the
16 * Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
21 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 *
26 * Authors:
27 * Jordan Justen <jordan.l.justen@intel.com>
28 *
29 */
30
31 #include "main/imports.h"
32 #include "main/bufferobj.h"
33 #include "main/macros.h"
34
35 #include "vbo.h"
36 #include "vbo_context.h"
37
38 #define UPDATE_MIN2(a, b) (a) = MIN2((a), (b))
39 #define UPDATE_MAX2(a, b) (a) = MAX2((a), (b))
40
41 /*
42 * Notes on primitive restart:
43 * The code below is used when the driver does not support primitive
44 * restart itself. (ctx->Const.PrimitiveRestartInSoftware == GL_TRUE)
45 *
46 * We map the index buffer, find the restart indexes, unmap
47 * the index buffer then draw the sub-primitives delineated by the restarts.
48 *
49 * A couple possible optimizations:
50 * 1. Save the list of sub-primitive (start, count) values in a list attached
51 * to the index buffer for re-use in subsequent draws. The list would be
52 * invalidated when the contents of the buffer changed.
53 * 2. If drawing triangle strips or quad strips, create a new index buffer
54 * that uses duplicated vertices to render the disjoint strips as one
55 * long strip. We'd have to be careful to avoid using too much memory
56 * for this.
57 *
58 * Finally, some apps might perform better if they don't use primitive restart
59 * at all rather than this fallback path. Set MESA_EXTENSION_OVERRIDE to
60 * "-GL_NV_primitive_restart" to test that.
61 */
62
63
64 struct sub_primitive
65 {
66 GLuint start;
67 GLuint count;
68 GLuint min_index;
69 GLuint max_index;
70 };
71
72
73 /**
74 * Scan the elements array to find restart indexes. Return an array
75 * of struct sub_primitive to indicate how to draw the sub-primitives
76 * are delineated by the restart index.
77 */
78 static struct sub_primitive *
find_sub_primitives(const void * elements,unsigned element_size,unsigned start,unsigned end,unsigned restart_index,unsigned * num_sub_prims)79 find_sub_primitives(const void *elements, unsigned element_size,
80 unsigned start, unsigned end, unsigned restart_index,
81 unsigned *num_sub_prims)
82 {
83 const unsigned max_prims = end - start;
84 struct sub_primitive *sub_prims;
85 unsigned i, cur_start, cur_count;
86 GLuint scan_index;
87 unsigned scan_num;
88
89 sub_prims = (struct sub_primitive *)
90 malloc(max_prims * sizeof(struct sub_primitive));
91
92 if (!sub_prims) {
93 *num_sub_prims = 0;
94 return NULL;
95 }
96
97 cur_start = start;
98 cur_count = 0;
99 scan_num = 0;
100
101 #define IB_INDEX_READ(TYPE, INDEX) (((const GL##TYPE *) elements)[INDEX])
102
103 #define SCAN_ELEMENTS(TYPE) \
104 sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
105 sub_prims[scan_num].max_index = 0; \
106 for (i = start; i < end; i++) { \
107 scan_index = IB_INDEX_READ(TYPE, i); \
108 if (scan_index == restart_index) { \
109 if (cur_count > 0) { \
110 assert(scan_num < max_prims); \
111 sub_prims[scan_num].start = cur_start; \
112 sub_prims[scan_num].count = cur_count; \
113 scan_num++; \
114 sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
115 sub_prims[scan_num].max_index = 0; \
116 } \
117 cur_start = i + 1; \
118 cur_count = 0; \
119 } \
120 else { \
121 UPDATE_MIN2(sub_prims[scan_num].min_index, scan_index); \
122 UPDATE_MAX2(sub_prims[scan_num].max_index, scan_index); \
123 cur_count++; \
124 } \
125 } \
126 if (cur_count > 0) { \
127 assert(scan_num < max_prims); \
128 sub_prims[scan_num].start = cur_start; \
129 sub_prims[scan_num].count = cur_count; \
130 scan_num++; \
131 }
132
133 switch (element_size) {
134 case 1:
135 SCAN_ELEMENTS(ubyte);
136 break;
137 case 2:
138 SCAN_ELEMENTS(ushort);
139 break;
140 case 4:
141 SCAN_ELEMENTS(uint);
142 break;
143 default:
144 assert(0 && "bad index_size in find_sub_primitives()");
145 }
146
147 #undef SCAN_ELEMENTS
148
149 *num_sub_prims = scan_num;
150
151 return sub_prims;
152 }
153
154
155 /**
156 * Handle primitive restart in software.
157 *
158 * This function breaks up calls into the driver so primitive restart
159 * support is not required in the driver.
160 */
161 void
vbo_sw_primitive_restart(struct gl_context * ctx,const struct _mesa_prim * prims,GLuint nr_prims,const struct _mesa_index_buffer * ib)162 vbo_sw_primitive_restart(struct gl_context *ctx,
163 const struct _mesa_prim *prims,
164 GLuint nr_prims,
165 const struct _mesa_index_buffer *ib)
166 {
167 GLuint prim_num;
168 struct sub_primitive *sub_prims;
169 struct sub_primitive *sub_prim;
170 GLuint num_sub_prims;
171 GLuint sub_prim_num;
172 GLuint end_index;
173 GLuint sub_end_index;
174 GLuint restart_index = ctx->Array.RestartIndex;
175 struct _mesa_prim temp_prim;
176 struct vbo_context *vbo = vbo_context(ctx);
177 vbo_draw_func draw_prims_func = vbo->draw_prims;
178 GLboolean map_ib = ib->obj->Name && !ib->obj->Pointer;
179 void *ptr;
180
181 /* Find the sub-primitives. These are regions in the index buffer which
182 * are split based on the primitive restart index value.
183 */
184 if (map_ib) {
185 ctx->Driver.MapBufferRange(ctx, 0, ib->obj->Size, GL_MAP_READ_BIT,
186 ib->obj);
187 }
188
189 ptr = ADD_POINTERS(ib->obj->Pointer, ib->ptr);
190
191 sub_prims = find_sub_primitives(ptr, vbo_sizeof_ib_type(ib->type),
192 0, ib->count, restart_index,
193 &num_sub_prims);
194
195 if (map_ib) {
196 ctx->Driver.UnmapBuffer(ctx, ib->obj);
197 }
198
199 /* Loop over the primitives, and use the located sub-primitives to draw
200 * each primitive with a break to implement each primitive restart.
201 */
202 for (prim_num = 0; prim_num < nr_prims; prim_num++) {
203 end_index = prims[prim_num].start + prims[prim_num].count;
204 memcpy(&temp_prim, &prims[prim_num], sizeof (temp_prim));
205 /* Loop over the sub-primitives drawing sub-ranges of the primitive. */
206 for (sub_prim_num = 0; sub_prim_num < num_sub_prims; sub_prim_num++) {
207 sub_prim = &sub_prims[sub_prim_num];
208 sub_end_index = sub_prim->start + sub_prim->count;
209 if (prims[prim_num].start <= sub_prim->start) {
210 temp_prim.start = MAX2(prims[prim_num].start, sub_prim->start);
211 temp_prim.count = MIN2(sub_end_index, end_index) - temp_prim.start;
212 if ((temp_prim.start == sub_prim->start) &&
213 (temp_prim.count == sub_prim->count)) {
214 draw_prims_func(ctx, &temp_prim, 1, ib,
215 GL_TRUE, sub_prim->min_index, sub_prim->max_index,
216 NULL);
217 } else {
218 draw_prims_func(ctx, &temp_prim, 1, ib,
219 GL_FALSE, -1, -1,
220 NULL);
221 }
222 }
223 if (sub_end_index >= end_index) {
224 break;
225 }
226 }
227 }
228
229 if (sub_prims) {
230 free(sub_prims);
231 }
232 }
233
234